Amplifier circuits



rent only whenzitiis-positive.

HAROLD" D. ARNOLD, OF'MAPIIEWOOD, NEW JERSEY, ASSIGNORYTO VVEEJII'ERINvELEC- TRIO COMPANY, INCORPORATED, OF. NEW YORK, N. Y., A CORPORATION OFNEW- YORK."

Application filed; \Tuly 1 1,

Toali'wh'omit may concern:

- Be. it known that I, HAROLD DE F. AR- rIoLn', a citizenof the UnitedStates, residing at Maplewood', in the county of Essex-and 5 Stateof'New Jersey, have invented certain new and useful: Improvements in-Amplifier @ircu'its, of which the following is a full, clear, concise,and: exact description.

The invention relates to electron discharge devices,'such as --aree1nployed for repeating or amplifying electrical impulses. It rela-testo the-reduction of: distortion of the wavesjtransmitted by such arepeater.

It is a known: fact that the relation between the-space current in anelectron repeatenrandtheg'rid:voltage is not a straight line.andrconse'quentlyi the.- variatioir in space currentydue to an appliedvoltage on the control-electrode or grid, is not a faithful copy 01":-theapplied-voltage. This variation in spme-current is commonly used forproducing. amplified: signals, although: the amplifier mayv also be usedasan oscillation generator in case a coupling between the input.andoutputcircuits is supplied.-

The distorting effect as shown-byxthenonlinear chara'cteristic.v may beminimized, accordingtothe-present invention, by making,

' use-0t the fact that the grid characteristic is also-nomlinearanditliat the-grid takes cure According to the: present invention aresistance is introduced: into the grid circuit so that at such times.-as the grid takes current theeffective grid potential is less than theimpressed electromottve force-by the potentiah drop across thisIBSiStBJlOQZ: This reducesv the effective grid potential" andconsequently reduces the space current thereby preventing distortion.Compensation is accordingly provided for the excessive increase in spacecurrent, which would otherwise take place When the grid becomes positiveand distortion of the repeated waves is prevented or atleast reduced.

For further details of the inventionreference may be made to thedrawings, in which 0 X to represent potential difference be:

AMTLIFIEB CIRCUITS.

1919." Serial No. 310,063.-

tween: grid and filament, then curves Ii, 2'

represent respectively the relation of plate;

The electrometivefoice whichiitiisedesirett to. repeat and) amplify isshown in Fig. 2 as derived fromeaigeneraton of sinusoidaileleeetromo-tive force a e, But: obviously. it may also come from ai couplingwitlrthe output; cirecuit as when the tube'is used as an oscillationgenerator; The: eiiective' potential due to this generaton, isrepresented. in Fig.-

along;th'e vertical. axis: ofrtime t the'axis 2%,.beingch0sen': to theleft o-f the main very tical axis Y byan amount 'Eucorresponding to theconstant voltagesuppliect by. the-bat tery 1 imFigQi.Thecorrespondlngz'variations in spacecurrent are show-n in theeusual. i

way: on '4 the horizontall axis -t A The amplitude oh the voltage'V asdrawn about the vertical time axisat, has been chosendarge-enoughisotllat the loopsZ representing; one halt wave-of: thisvoltage: will; extend to the.- right- "ofthe: extensimn 015 themainiaxis Y, whichmorresponds-to;thaticone dition Of-ztllfi gridbeingipositive withirespcctto. the filamentii The portion. V- -E" repre.cents the-amountiby whichlthe-g'ridris posts tive with respect to thefilament, that is, the amount by which the electromotive force to berepeated is larger than the steady electr0-, H

motive force E.

Two cases are to be noted. In the first I place consider that there isno resistance in the grid; circuit so that the grid potential is equalto V+ E even when the grid goes positive and takes current, due topicking up electronsffrom the cathode. ,Then' the grid potential andspace current will be' a s show by the curves markeda and a,respectively The space current variation is a much distorted copy of theelectromotive force which it is desired to repeat.

Point 3on the curve 04 is determined, of

fies

course, by projecting the point curve 2 in a vertical direction until itmeets the curve/I at point 5 and then projecting the point 5 to theright along the timeaxis t the same distapce that the point 4 isdistance from 0 along the axis Ot The other points on the'curvea arelocated in a similar manner.

Now suppose a resistance-r is introduced into the grid circuit The gridpotential. V l-E will now beequal to e-l-E except for a time whencurrent is flowing in the grid circuit, during which time it will beless than 6+E' by an' amount I R where I is the current flowing in thegrid circuit. This l R drop occurs at just the proper time to limit theotherwise undesirably high value of space curren t which would otherwiseoccur and the value of the resistance. 1*, should be chosen with dueregard to the operating characteristics of the tube and to theelectro'moti ve force'to be amplified.

wlt has been found that when this inven tion is applied to anoscillation generator there is :a reduction in the value of the secondharmonic which would otherwise be present and there'is a consequent gainin the power output at the fundamental frequency.

"While for convenience of exposition the source, e has been descnbed assinusoidal, the above considerations hold for electromotive .forces ofany wave form.

What is claimed is: 1. The method of producing substantially faithfulcopy of an impulse to be repeated by an electric discharge device havingan anode, a cathode and a control electrode, 'which method comprisesovercoming the distortion of saidimpulse which tends to take plaee'whenthe impulseis of t on the an amplified Leanssa sufficient strength tomake the control elec trode positive to the cathode by causing thecontrol electrode potential to respond nonlinearly to changes in thevoltage of the impulse to be repeated. 3

2. In combination, an incoming line and means associated with said linefor amplifying impulses'from said line substantially without distortion,said means including a vacuum tube having an anode, a cathode and acontrol electrode, a source of voltage connected between said anode andcathode, means-for maintainingsaid control electrode negative at timeswith respect to said cathode, and a resistance in series with said line,said control electrode and said cathode'oit such a value with respect tothe strength of the impulses to be repeated and the characteristics ofthe amplifier as to substantially prevent distortion of the repeatedimpulse due to the curvilinear relation between control electrodepotential and anode, current,

3. An electron discharge amplifier for amplitying electrical impulses,said amplifier having an input circuit including a control i electrode,and means associated with said input circuit for preventing saidamplifier from producing substantial distortion ,in

said impulses when said control electrode becomes positive with respectto said cathode, said means having negligible efiect on theamplificationof said impulses when said grid negative with respect tothe cathode,-

a source of impulse t0'be repeated without change of character andotsuficient' value to overcome said first-mentioned source whereby saidgrid. becomes at times posi tive with respect to said cathode, and meansto reduce distortion when said grid becomes positive. y

In witness whereoffilfhereunto subscribe myrname this 9th day ofJuly,l). 1919;

rumour; neurone.

control electrode isnegative with respect'to

